Abstract
Underground structures, such as tunnels, are vital for ensuring all kinds of transportation; and being buried under the surface makes them exposed to soil dynamics. Added to the moderate seismic activity in Morocco, the stability of tunnels is put to the test. This paper examines the interaction between the ZAM (Zaouit Ait Mellal) twin tunnels between the cities of Marrakesh and Agadir, using the Difference Element Method provided by FLAC 2D software. The acceleration is introduced as the one related to the historic event of El centro 1940 with free-field boundary conditions in the numerical model, with three configurations: tunnel 1 without tunnel 2, tunnel 2 without tunnel 1 and tunnel 1 with tunnel 2. The results of the simulations indicate that the differences values of the maximum displacement, axial force and bending moment on structural elements are very noteworthy from the configuration of the tunnel (single) to the twin tunnels in order to prove the interaction between these latter under seismic loading.
Highlights
In recent years, Morocco has experienced considerable development in infrastructure with the implementation of large projects such as road and rail networks and underground structures
This article presents a seismic analysis of the ZAM twin tunnels, using the numerical simulation of the explicit finite difference method provided by FLAC 2D (Fast Lagrangian Analysis of Continua) (FLAC 2005 ) [11], software by introducing the data of El centro 1940 earthquake to see his impact between the tunnels on the maximum displacements in different points on structural elements, for that we chose 3 configurations as follows: -Tunnel 1 without tunnel 2 -Tunnel 2 without tunnel 1 -Tunnel 1 with tunnel 2
The numerical simulation under seismic loading have been done, and the results are in terms of maximum displacement, Axial force and bending moment in the structure elements at dynamic time of 8.14 s, due to the location of the Peak Ground Acceleration value in the accelerograms in the range [0s, 8s].The estimation of these parameters around the tunnel requires special attention because it has a major influence on the design of lining, for the verification of stability
Summary
Morocco has experienced considerable development in infrastructure with the implementation of large projects such as road and rail networks and underground structures. The latter, in particular tunnels built in areas exposed to seismic activities must be and essentially resistant to soil dynamics. This fact is illustrated in many cases of tunnel damage due to seismic events, such as the ones observed during the 1995 Kobe earthquake in Japan at the Daikai subway station [1,2], the 1999 Chi Chi earthquake in Taiwan investigated by Wang et al [3], which showed the 49 tunnels of 57 (in total) sustained damage from this earthquake and the 1999 Kocaeli earthquake in Turkey at of the Bolu tunnel [4]. This article presents a seismic analysis of the ZAM twin tunnels, using the numerical simulation of the explicit finite difference method provided by FLAC 2D (Fast Lagrangian Analysis of Continua) (FLAC 2005 ) [11], software by introducing the data of El centro 1940 earthquake to see his impact between the tunnels on the maximum displacements in different points on structural elements, for that we chose 3 configurations as follows: -Tunnel 1 without tunnel 2 -Tunnel 2 without tunnel 1 -Tunnel 1 with tunnel 2
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